1. Field of the Invention
This invention relates to a method for marking the surface of an object, and more particularly, to a method for selectively imprinting a plurality of individual marks in the surface of an object to form a bar code message in the surface of the object.
2. Description of the Prior Art
Utilizing a dot matrix marking device that includes a plurality of individual marking pins to imprint alphanumeric characters in the surface of a workpiece is well known.
British Pat. No. 2,002,694 discloses a programmable dot matrix type of engraver that is operable to imprint a selected size of alphanumeric characters into the surface of a workpiece. An engraving tool is supported on an arm which is movable on a carriage by a lead screw rotated by a stepping motor. The carriage is movably mounted on a horizontal arm that is, in turn, supported by a vertical column above a base on which the workpiece to be marked is stationarily positioned. With this arrangement, the engraving tool is movable along horizontal x and y axes. The engraving tool includes a punch which is remotely controlled by a central processing unit through a solenoid operated air valve to imprint the desired alphanumeric character into the surface of a workpiece.
U.S. Pat. No. 4,506,999 discloses a pneumatically controlled apparatus that includes an array of seven pins that are selectively operated to imprint alphanumeric characters in a workpiece. The seven pins are moved across the workpiece to selectively mark the workpiece with the desired alphanumeric characters. The angular arrangement of the pins determines the height of the characters and rotation of the head adjusts the angle of the line of pins.
While it has been suggested by the prior art devices to utilize a plurality of marking pins to imprint a plurality of individual marks in the surface of a workpiece to form an alphanumeric character message thereon, there is a need for a method of utilizing a plurality of marking pins to imprint a plurality of individual marks in the surface if a workpiece to provide a bar code message in the surface of the workpiece. The bar code message must be imprinted in the surface of the workpiece in such a manner that the message is capable of being read by standard, commercially obtainable bar code reading devices.